This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7119 from my application BIDIRECTIONAL LIGHT TRANSMITTING AND RECEIVING DEVICE filed with the Korean Industrial Property Office on Jul. 12, 2000 and there duly assigned Serial No. 27989/1999.
1. Field of the Invention
The present invention relates to a bidirectional light transmitting and emitting device, and more particularly, to a bidirectional light transmitting and emitting device having a light emitter emitting an optical signal onto another receiver and a light receiver receiving the optical signal transmitted from another light emitter, both light emitter and receiver integrated on a substrate.
2. Description of the Related Art
A light transceiver has been used for emitting an optical data signal to be transmitted or receiving an optical data signal transmitted. A light emitter emitting the optical data signal is mounted on the light transceiver and spaced apart from a light receiver receiving the optical data signal. For example, in a conventional light transmitting and receiving device shown in FIG. 1, a first optical signal emitted from a light emitter 3 of a first light transceiver 1 is detected by a light receiver 7 of a second light transceiver 5 while a second optical signal emitted from a light emitter 8 of the second light transceiver 5 is detected by a light receiver 4 of the first light transceiver 1. Optical fibers 2 are disposed between the first and second transceivers 1, 5 to transmit the respective first and second optical signals and form transmission passageways between the light emitters 3, 8, and the light receivers 4, 7, respectively. A condensing lens 6 is attached to each end of optical fibers 2 for improved light transmission efficiency. First light transceiver 1 includes a driver 13 driving light emitter 3 in response to an input data signal, and an amplifier 14 amplifying a first current signal detected by receiver 4. Second light transceiver 5 includes a driver 18 driving light emitter 8 in response to another input data signal, and an amplifier 17 amplifying a second current signal detected by receiver 7.
In the conventional light transmitting and receiving device, an edge emitting laser or a light emitting diode is used for light emitter 3, 8. The light emitted from light emitter 3 is an optical signal appropriately modulated from a data signal to be transmitted. The optical signal is transferred through one end of optical fiber 2, detected by receiver 7, converted into a current signal, and then demodulated into an original data signal by amplifier 17. The light emitted from the light emitter 8, which is also an optical signal appropriately modulated from another data signal, is transmitted 8 to first light transceiver 1 in the same manner as described above.
The conventional light transmitting and receiving device, however, needs two channels for transmission and reception of the optic signals. The structure of the device is complicated because of the increased number of parts. The manufacturing process of the conventional light transmitting and receiving device is difficult. Moreover, these problems become more serious since a plurality of the light transmitting and receiving devices are assembled for multi-channel data transmission requiring more transmission and reception channels.
It is an object of the present invention to provide a light transmitting and receiving device able to transmit one signal and receive another signal through a single channel.
It is another object to provide a light transmitting and receiving device able to connect one of light transmitting and receiving device to another light transmitting and receiving device through a clear path.
It is yet another object to provide a light transmitting and receiving device able to reduce the number of optic fiber cables connected between light transmitting and receiving devices.
It is still another object to provide a light transmitting and receiving device able to reduce the size of a light emitter and a lighter receiver.
It is a further object to provide a light transmitting and receiving device able to reduce a manufacturing cost by integrally forming a light emitter and a light receiver on a single substrate and reducing the number of the optic fiber cables.
It is also an object to provide a light transmitting and receiving device able to precisely and accurately detecting an optical signal by using a relatively high absorbency with respect to a particular wavelength of light.
These and other objects may be achieved by providing a light transmitting and receiving device including a first light transceiver having at least one first light device unit having a first vertical cavity surface emitting laser (VCSEL) portion generating and emitting a light beam in the stack direction of semiconductor material layers, a first light receiving portion combined with the first VCSEL portion receiving an incident beam entering around the first VCSEL portion, and a first driver for driving the first VCSEL portion, a second light transceiver having at least one second light device unit having a second VCSEL portion generating and emitting a light beam in the stack direction of semiconductor material layers, a second light receiving portion combined with the second VCSEL receiving an incident beam entering around the second VCSEL portion, a second driver for driving the second VCSEL portion, wherein a signal transmission and reception between the corresponding, first and second light device units is performed through the same passageway.
Each of the first and second VCSEL portions includes a substrate, a lower electrode formed over the back side of the substrate, a subreflector, an active layer and an upper reflector formed over the substrate in sequence, and an upper electrode formed at the top edge of the upper reflector. The first and second light receiving portions share the substrate and the lower electrode with a corresponding combined VCSEL portion and includes a first semiconductor material layer formed on the substrate to surround the combined VCSEL portion, a predetermined distance apart from the combined VCSEL portion, a second semiconductor material layer and a third semiconductor material layer formed over the first semiconductor material layer in sequence, and a detecting electrode formed on the top edge of the third semiconductor material layer.
The bidirectional light transmitting and receiving device includes a common layer between the substrate and the VCSEL portion and the light receiving portions in at least one of first and second light device units. The common layer is formed of the same material and with the same number of layers as the subreflector. The first semiconductor material layer is formed of the same material and with the same number of layers as the subreflector. The second semiconductor material layer is formed of the same material to have the same thickness as the active layer, and the third. semiconductor material layer is formed of the same material and with the same number of layers as the upperreflector.
The bidirectional light transmitting and receiving device includes at least one optical fiber cable arranged on the optical passageway between the corresponding first and second light device units to transmit an optical signal, wherein the signal transmission and reception between the corresponding first and second light device units is performed through the optical fiber cable.
The bidirectional light transmitting and receiving device includes a first light transceiver including a first printed circuit board (PCB) and at least one first light device unit mounted on the first PCB, the first light device unit including a first light emitter for emitting a light beam in an approximately vertical direction to the first PCB and a first light receiver for receiving a light beam entering around the first light emitter, a second light transceiver including a second PCB and at least one second light device unit mounted on the second PCB, the second light device unit having a second light emitter for emitting a light beam in an approximately vertical direction to the second PCB and a second light receiver for receiving a light beam entering around the second light emitter, and at least one optical fiber cable arranged between the corresponding first and second light device units to transmit an optical signal, wherein a signal transmission and reception between the corresponding first and second light device units is performed through the single optical fiber cable.